Shape, size, hydration and flow behavior of nitrocellulose lacquer emulsion in absence and presence of urea

Abstract

Viscometric and optical microscopic experiments, performed on nitrocellulose lacquer emulsions in the absence (Emulsion I) and presence (Emulsion II) of urea, indicate that in aqueous concentrated solutions at 30 C the emulsion droplets are spherical and non-spherical in shape, respectively. Assuming spherical shape for both emulsions, the size and volume of the aggregated particle (M_v), radius of gyration (R_g), hydrodynamic radius (Rh), diffusion coefficient (D), the correlation time for aggregate rotation (T_r), translational diffusion (T_D) and effective aggregation time (T_a) have been derived. The viscosity data for both emulsions were analyzed in terms of the Einstein, Moulik and Jones-Dole equations. Emulsion II was more hydrated than Emulsion I, although the intrinsic viscosity (η) of Emulsion II is nearly 1.5 times greater than that of Emulsion I. The Huggins and Thomas equations have been compared for both emulsions, and it has been concluded, in light of the proposed Huggins-Thomas-Mandal equation, that the Thomas constant k1 should be 12.50 for perfect spherical shape of the particles in dilute solutions, instead of the 10.05 originally proposed by Thomas.